Checked-by-default means, by definition, it is opt-out as you are opted-in by default. It just has to be possible to opt-out and, if opted-in, unsubscribe at a

Checked-by-default means, by definition, it is opt-out as you are opted-in by default. It just has to be possible to opt-out and, if opted-in, unsubscribe at a later date (usually a small, hard to notice link in the legalese of the spam email).